The captain- a psychopath?
Collect all the guffers, and update your ability to dive deeper. And keep going deeper- don't be shy! You'll run into.... a whole new world, see some interesting and terrifiying things.
The boss is unbeatable. There is only a ending, and you can accomplish this without buying everything at first.
The captain seems to have some kind of anti-gravity that makes swimming in all directions difficult, but also one that somehow ensnares you, making it difficult to really leaving the breathable water. (Even if you were able to, your equpiment would malfunction, and you'd drown before you'd reach the surface) The captain will also hunt you down.
However, if I were to rely on his words, espically at the end, I've came to the conclusion that the captain is... a psychopath.
He leds you to be eaten by the titanic creatures, and then ask you how does it feel to be on the other half of the hunt- as the prey. This was his plan all along. Then one would realize that all thes guffers was been planted, because the captain has marked you, the diver, as his newest prey. Now, with this new perpection, go on and read his 'diary'. The captain was wondering how it would feel to be hunted, to be an prey... and he forced you into this positon.
Remember when you, as the diver, has an nightmare where all these titanic creatures slowly approches you to consume you? THAT'S A PRECOGNITION! Only when you're really in that area with all these mysterious, devouring creatures, you're truely awake... and thus, you've ended the game when you are killed in this area.
But what this game's really all about is the emotion. The wonder at the life underwater, the sense of aventure and of exploration as you try to see every species and guffers, the relaxation of being the top predator; the sense of relief of it all being a nightmare... and then, fear and confusion as you're suddenly thrown in a new, creepy world where the usual law of nature no longer applies (With the water being breathable), where you are no longer the top predator, but a mere defendless prey, delaying the inevitable, fleeing from creatures too titanic to be seen entirely on the screen, and betrayal by seeing that the captain has led you all along to be either consumed by these fiendish creatures or to be impaled like a mere fish... and then, nothing.
Because this is not a nightmare. To your horror, you've discovered that you've died for real this time, as a defendless prey.
I love this game. The ending caught me off surprise, and this is what makes such an gameplay amusing, since it will make your perpection change sharply once one've discovered the truth.